Exploring, drilling, completing, and operating hydrocarbon and other wells are generally complicated, time consuming and ultimately very expensive endeavors. In recognition of these expenses, added emphasis has been placed on well access, monitoring and management throughout its productive life. Ready access to well information as well as well intervention may play critical roles in maximizing the life of the well and total hydrocarbon recovery. Along these lines, information-based or ‘smart’ management often involves relatively straight forward interventional applications. For example, introduction of a shifting tool so as to start, stop or adjust well production via opening or closing a sliding sleeve or valve may not be an overly-sophisticated maneuver. Nevertheless, continued effective production from the well may be entirely dependent upon such tasks being successfully performed.
While fairly straight-forward, the effectiveness of a shifting tool application may be quite significant, as indicated. In a specific example, consider a well having various isolated production zones. As alluded to above, the overall profile of the well may be monitored on an ongoing basis. Thus, over the life of the well, as certain zones begin to become depleted, produce water or require some form of remediation, an information-based intervention may ensue. More specifically, where a zone of concern is outfitted with a sliding sleeve, an intervention with a shifting tool may take place whereby the tool is directed to the sleeve in order to manipulate a closure thereof. As such, the zone may be closed off in a manner that allows continued production to come from more productive, less contaminant prone, adjacent zones.
The use of a shifting tool as described above generally involves the deployment of the tool to the location of the sleeve or other shiftable feature of the well. This may be accomplished by way of wireline deployment, coiled tubing, tractoring, or any number of conveyance modes, depending on the nature of the well and location of the shiftable feature. Regardless, the tool is outfitted with extension members, generally referred to as ‘dogs’, which are configured to latch onto the shiftable feature once the tool reaches the downhole location. In many cases, the dogs may be configured to be of a lower profile during deployment to the shiftable feature. Whereas, upon reaching the location, the dogs may be radially expanded for latching onto the shiftable feature such that it may be shifted in one direction or another.
Unfortunately, the effectiveness of the tool faces a variety of limitations associated with the expansion and retraction of the dogs. For example, in a more basic model, the latching features of the tool consist of matching profile areas incorporated into bow or leaf springs of the tool. Thus, the tool traverses the well with a slightly expanded bow portion that ultimately comes into interface with the shiftable feature. Once interlocked, axial forces of the tool are naturally translated outwardly through the bows to a degree. However, aside from the drawback of more limited clearance, between the tool and the well wall, during deployment, the capacity of a bow is also structurally limited. That is, where resistance to shifting is significant, the bow may simply retract without affecting any shifting. Alternatively, bow-type designs may be utilized which avoid collapse once interlocked so long as the shifting is in one direction. That is to say, a collapse of some form must still be built into the tool so as to allow for the disengagement of the tool following shifting without involvement of surface control. As a result, such a tool still lacks assuredness of shifting in both directions.
Therefore, in order to provide more effective multi-directional shifting capacity, the tool may be of an ‘intelligent’ design where dogs are more affirmatively radially expanded, based when the tool is known to be properly located for shifting. For example, such tools may utilize dogs which are retracted to within the body of the tool during conveyance through the well and then hydraulically expanded outwardly upon reaching the shiftable feature. Unlike bow configurations, such tools are able to provide multi-directional shifting without concern over premature collapse. Unfortunately, however, such tools may be of fairly limited reach.
A greater reach may be provided through the use of dogs which are mechanically driven to expansion. Such is the case where the dogs are retained below a sleeve which may be retracted axially so as to release the dogs radially via spring force upon encountering the shiftable feature. As a practical matter, this results in dogs that are either fully deployed or fully retracted. The ability to centralize or perform tasks with the dogs semi-deployed is lacking in such configurations. Indeed, wells and shiftable features of variable diameters present significant challenges to all types of conventionally available shifting tool options.